16 01 00 (557)

Functional description for fuel supply system

E38, E39, E46, E52, E53
General

Fuel supply systems in petrol engines

Fuel system

The fuel pump in the fuel tank generates pressure in the fuel system, which is set by the pressure regulator valve to a certain level.

 

Tank safety valve

The tank safety valve is a closed system that is bled via a carbon canister. The carbon in the carbon canister is stored as granules. The large surface of the granules traps the fuel vapour, that occurs in the fuel tank. The carbon canister needs to be refreshed regularly in order to be able to continue to store fuel vapour. This is done by flushing it with fresh air from the intake pipe. This process is controlled by the engine control unit.

Diesel engine fuel supply system

Fuel system

The fuel pump in the fuel tank supplies the engine with fuel. Two types of high pressure pump are used for direct injection.

  1. The power distribution box injection pump. This supplies each cylinder directly with fuel via individual injector nozzles.
  2. The high pressure pump for the common rail systems. This generates the required pressure in the fuel injection pipe for all injector nozzles.

With common rail systems another pump (inline pump, M57/geared pump, M67) is connected between the high pressure pump and the fuel pump. This pump aids the fuel pump in the fuel tank during times of high fuel requirement.

 

Tank safety valve

Diesel fuel is slow-evaporating, therefore no carbon canister is required. The fuel tank is ventilation directly into the atmosphere.

1. Fuel supply system E38/39

1.1 Part designation

1. Fuel tank (E38 steel, E39 plastic) 16. Float valve (USA only)
2. Fuel pump 17. Fuel return line
3. Surge tank 18. Fuel delivery line
4. Suction jet pump 19. Fuel filter
5. Pressure limit valve 20. Pressure regulator
6. Run-out protection valve 21. 3/2-way valve (M52 US only)
7. Pressure test line (USA only) 22. Fuel injection pipe
7. Refuelling tank ventilation line (worldwide) 23. Purge air line
8. Non-return valve 24. Engine control unit
9. Fuel filler pipe 25. Tank vent valve
10. Fuel filler cap 26. Intake pipe
11. Fuel tank expansion line 27. Vacuum line (leak diagnosis pump USA only)
12. Refuelling tank ventilation line (USA only) 28. Carbon canister
12. Service tank ventilation line (worldwide) 29. Evaporation line
13. Service tank ventilation line 30. Leakage diagnosis pump (USA only)
14. Expansion tank 31. Tank leakage diagnosis module (USA only)
15. Roll-over valve 32. Dust filter (USA only)

1.2 Functional description (see also graphics 1.4/1.5/1.6/1.7/1.8)

Fuel system

The saddle-shaped fuel tank contains the surge tank with an electric fuel pump on its right side. The surge tank ensures that the fuel pump is properly supplied in all vehicle operating conditions. The suction jet pump built into the floor of the surge tank supplies the surge tank with fuel. The fuel is pumped from the left side of the fuel tank into the surge tank via the suction jet pump integrated in the tank expansion line. Both suction jet pumps are operated by the fuel return line.

The pressure limit valve controls the required pressure to operate the suction jet pump. The run-out protection valve secures the fuel return line. If the pressure falls if the fuel return line is damaged or disconnected, the valve closes. This prevents the fuel from running out of the fuel tank in extreme vehicle positions (rollover, on an incline etc.). The non-return valve prevents the fuel from sloshing back into the filler pipe after the fuel pump nozzle is shut.

Fuel supply to the engine

M52TU (see graphic 1.5, view A)

The fuel is routed from the electric fuel pump via the fuel delivery line and the fuel filter to the fuel injection pipe. The fuel flows back into the fuel tank via the pressure regulator on fuel injection pipe and the fuel return line.

M52 USA and M73 (see graphics 1.5/1.6)

The fuel is routed from the electric fuel pump via the fuel delivery line and the fuel filter to the fuel injection pipe. The reverse flow into the fuel tank takes place via the 3/2-way valve (see view A), the pressure regulator and the fuel return line. This engine fuel circuit with reverse flow from the fuel injection pipe is used for engine start and for a set time less than 1 minute after this. After this phase the 3/2-way valve triggers and stops the fuel reverse flow from the fuel injection pipe. At the same time the branch line directly on the fuel filter is activated by the 3/2-way valve on the pressure regulator (see view B). The fuel injection pipe is now free from return fuel.

M62TU/54 (see graphic 1.4, view B and graphics 1.7/1.8)

The pressure regulator and fuel filter are incorporated in a single unit. The fuel is routed from the electric fuel pump via the fuel delivery line and the fuel filter/pressure regulator to the fuel injection pipe. The fuel injection pipe is return-free. The fuel flows directly from the fuel filter/pressure regulator back into the fuel tank.

Tank safety valve USA (see graphics 1.6/1.7/1.8)

The fuel tank is vented during refuelling via the refuelling vent line.

Because of its large cross-section, the refuelling ventilation line directs the displaced volume (fuel vapours) at high speed through the expansion tank to the carbon canister. The activated carbon retains the fuel contained in the fuel vapours. The cleaned air is discharged to the atmosphere via the evaporation line, the leak diagnosis pump/tank leak diagnosis module and the dust filter. Ventilation during vehicle operation is done in the same way via the refuelling tank ventilation line and the service tank ventilation line. The condensed components of the fuel vapour go from the expansion tank via the service tank ventilation line back into the fuel tank. The float valve in the refuelling tank ventilation line (E39 only) is closed by the rising fuel if the tank is overfilled. This prevents the expansion tank from being overfilled. The roll-over valve on the top side of the expansion tank closes if the vehicle rolls over. This prevents fuel from spilling into the carbon canister. The carbon canister is regenerated by purging with fresh air. The engine control unit opens the tank vent valve. This means there is an intake pipe vacuum at the purge air line. This flushes the carbon canister with fresh air via the evaporation line, the leakage diagnosis pump/the tank leakage diagnosis module and the dust filter. The fuel constituents bound by the activated carbon are flushed out by the supplied air and directed via the purge air line to the engine for combustion. This operation is only possible while the engine is running.

Tank safety valve worldwide (see graphics 1.4/1.5)

See tank safety valve USA with the following exceptions:

  1. The fuel tank ventilation during refuelling takes place via the refuelling vent line which directs the displaced volume into the fuel filler neck. Instead of the large cross-section refuelling tank ventilation line (USA), there is a second service tank ventilation line with a small cross-section. There is no float valve.
  2. The carbon canister has a smaller capacity.
  3. There is no leakage diagnosis pump or tank leakage diagnosis module and dust filter

Leakage diagnosis for the tank ventilation system USA (see graphics 1.6/1.7/1.8)

The leakage diagnosis pump (see graphics 1.6/1.7) / tank leakage diagnosis module (see graphic 1.8) are used for leak diagnosis for the tank ventilation system within the on-board diagnosis laid down by legislation. The tank ventilation system is pressurised and the pressure loss is detected in the event of a leak.In the case of the leakage diagnosis pump, the pressure loss is measured over the post-pumping time. The pump is operated with a vacuum from the intake pipe via the vacuum line.The diagnostic module for tank leaks is activated by the DME control unit and detects the pressure loss by way of the power consumption of the integrated pump. The air required for this purpose is supplied via the dust filter. Both systems are actuated by the engine control unit.The pressure test line establishes the connection between fuel tank and fuel filler neck. This enables a leak to be detected in the fuel filler pipe-fuel tank cap area.

Determining fill level in fuel tank:

The fuel level is measured by means of lever sensors on both sides of the fuel tank. The right-hand lever sensor is integrated into the fuel delivery unit. The left-hand lever sensor is located in the left sensor unit. The combination of the determined ohm values from the right and left lever sensor produces the actual fluid level in the fuel tank.

1.3. Operating data, fuel system

Pressure regulator: 3.5 barS62 5 bar)

Operating pressure of the suction jet pumps: 1 - 1.3 bar

 

1.4. Fuel supply system E38/39 M52TU/M54/M62TU
1.5. Fuel supply system E38 M73
1.6 Fuel supply system E38/39 M52/73 USA
1.7 Fuel supply system E38/39, M62 USA (LDP)
1.8 Fuel supply system E39, M54/62 USA (TLDM)

2. Fuel supply system E46

2.1 Part designation

1. Fuel tank (plastic) 18. Roll-over valve
2. Fuel pump 19. Float valve (USA only)
3. Surge tank 20. Fuel filter
4. Pressure limit valve 21. Pressure regulator
5. Run-out protection valve 22. 3/2-way valve (M52 US only, M73)
6. Suction jet pump 23. Fuel injection pipe
7. Fuel tank expansion line 24. Engine control unit
8. Non-return valve 25. Intake pipe
9. Fuel filler pipe 26. Tank vent valve
10. Fuel filler cap 27. Purge air line
11. Pressure test line (USA only) 28. Tank ventilation line
11. Refuelling tank ventilation line (worldwide) 29. Vacuum line (leak diagnosis pump USA only)
12. Fuel delivery line 30. Evaporation line
13. Fuel return line 31. Carbon canister
14. Service tank ventilation line 32. Carbon canister (USA only)
15. Refuelling tank ventilation line (USA only) 33. Leakage diagnosis pump (USA only)
15. Additional tank ventilation line (Japan) 34. Dust filter (USA only)
16. Service tank ventilation line 35. Tank leakage diagnosis module (USA only)
17. Expansion tank  

2.2 Functional description (see also graphics 2.4/2.5/2.6/2.7)

Fuel system

The saddle-shaped fuel tank contains the surge tank with an electric fuel pump on its right side. The surge tank ensures that the fuel pump is properly supplied in all vehicle operating conditions. The fuel is pumped from the right side of the fuel tank into the surge tank via the suction jet pump integrated in the tank expansion line. The suction jet pump is operated via the fuel return line.

The pressure limit valve controls the required pressure to operate the suction jet pump. The run-out protection valve secures the fuel return line. If the pressure falls if the fuel return line is damaged or disconnected, the valve closes. This prevents the fuel from running out of the fuel tank in extreme vehicle positions (rollover, on an incline etc.). The non-return valve prevents the fuel from sloshing back into the filler pipe after the fuel pump nozzle is shut.

Fuel supply to the engine

M43TU/52TU (see graphic 2.4, view A)

Description see fuel supply system E38/39, 1.2 functional description, engine fuel supply M52TU.

M52 USA and M73 (see graphics 1.5/1.6)

Description see fuel supply system E38/39, 1.2 functional description, engine fuel supply M52 USA and M73.

M54 (see graphic 1.4, view B and graphics 1.7/1.8)

Description see fuel supply system E38/39, 1.2 functional description, engine fuel supply M54/62TU.

Tank safety valve USA (see graphics 2.6/2.7)

The fuel tank ventilation during refuelling takes place via the refuelling vent line.Because of its large cross-section, the refuelling ventilation line directs the displaced volume (fuel vapours) at high speed through the expansion tank to the carbon canister. The activated carbon retains the fuel contained in the fuel vapours. The cleaned air is discharged to the atmosphere via the evaporation line, the leak diagnosis pump/tank leak diagnosis module and the dust filter. Ventilation during vehicle operation is done in the same way via the refuelling tank ventilation line and the service tank ventilation line. The condensed components of the fuel vapour go from the expansion tank via the left service tank ventilation line back into the fuel tank. The float valve in the expansion tank is closed by the rising fuel if the tank is overfilled. This prevents the expansion tank from being overfilled. The roll-over valve on the top side of the expansion tank closes if the vehicle rolls over. This prevents fuel from spilling into the carbon canister. The carbon canister is regenerated by purging with fresh air. The engine control unit opens the tank vent valve. This means there is an intake pipe vacuum at the purge air line. The carbon canister is purged in this way. The fresh air required for this is fed from the leakage diagnosis pump/the tank leakage diagnosis module and the dust filter. The fuel constituents bound by the activated carbon are flushed out by the supplied air and directed via the purge air line to the engine for combustion. This operation is only possible while the engine is running.

Tank safety valve worldwide (see graphic 2.4)

See tank safety valve USA with the following exceptions:

  1. The fuel tank ventilation during refuelling takes place via the refuelling vent line which directs the displaced volume into the fuel filler neck. Instead of the large cross-section refuelling tank ventilation line (USA), there is a second service tank ventilation line with a small cross-section. There is no float valve.
  2. The carbon canister has a smaller capacity.
  3. There is no leakage diagnosis pump or tank leakage diagnosis module and dust filter
  4. For vehicles in Japan an additional tank ventilation line with a float valve (instead of a refuelling tank ventilation line (USA)) is integrated into the expansion tank, which is connected to the refuelling-tank ventilation line (worldwide).This modification is required due to the fuel in Japan with more outgassing (see graphic 2.5).

Leakage diagnosis for the tank ventilation system USA (see graphics 2.6/2.7)

Description see fuel supply system E38/39, 1.2 functional description, leak diagnosis for the tank ventilation system USA.

Determining fill level in fuel tank:

The fuel level is measured by means of lever sensors on both sides of the fuel tank. The right-hand lever sensor is integrated into the fuel delivery unit. The left-hand lever sensor is located in the left sensor unit. The combination of the determined ohm values from the right and left lever sensor produces the actual fluid level in the fuel tank.

2.3. Operating data, fuel system

Pressure regulator: 3.5 bar

Operating pressure of the suction jet pumps: 1 - 1.3 bar

2.4 Fuel supply system E46 M43TU/M52TU/54
2.5 Fuel supply system E46 M43TU/M52TU/M54 Japan
2.6 Fuel supply system E46 M52 USA
2.7 Fuel supply system E46, M54 USA

3. Fuel supply system E52

3.1 Part designation

1. Fuel tank (plastic) 16. Condensate container
2. Fuel pump 17. Fuel return line
3. Surge tank 18. Fuel delivery line
4. Suction jet pump 19. Pressure regulator
5. Non-return valve 20. Fuel filter
6. Fuel filler pipe 21. Fuel injection pipe
7. Pressure test line (USA only) 22. Engine control unit
8. Fuel filler cap 23. Tank vent valve
9. Pressure limit valve 24. Intake pipe
10. Run-out protection valve 25. Purge air line
11. Roll-over valve 26. Tank ventilation line
12. Service tank ventilation line 27. Carbon canister
13. Refuelling tank ventilation line 28. Evaporation line
14. Pressure-retaining valve 29. Dust filter
15. Throttle 30. Tank leakage diagnosis module (USA only)

3.2 Functional description (see also graphic 3.4)

Fuel system

The fuel tank contains the surge tank with the fuel pump. The surge tank ensures that the fuel pump is properly supplied in all vehicle operating conditions. The suction jet pump built into the floor of the surge tank supplies the surge tank with fuel. The pressure limit valve controls the required pressure to operate the suction jet pump. The run-out protection valve secures the fuel return line. If the pressure falls if the fuel return line is damaged or disconnected, the valve closes. This prevents the fuel from running out of the fuel tank in extreme vehicle positions (rollover, on an incline etc.). The fuel filler pipe is split into two in the fuel tank. This ensures quicker filling times. The two non-return valves prevent the fuel from sloshing back into the filler pipe after the fuel pump nozzle is shut.

Fuel supply to the engine

Description see fuel supply system E38/39, 1.2 functional description, engine fuel supply M54/62.

Tank safety valve USA

The fuel tank ventilation during refuelling takes place via the refuelling vent line.Because of its large cross-section, the refuelling ventilation line directs the displaced volume (fuel vapours) at high speed through the condensate tank to the carbon canister. The activated carbon retains the fuel contained in the fuel vapours. The cleaned air is discharged to atmosphere via the evaporation line, the tank leak diagnosis module and the dust filter. Ventilation during vehicle operation is done in the same way via the refuelling tank ventilation line and the service tank ventilation line. The condensed components of the fuel vapour go from the condensate tank via the service tank ventilation line back into the fuel tank. The roll-over valves of the tank ventilation lines prevents fuel from getting into the condensate tank in extreme driving condition and positions. The throttle in the right-hand service tank ventilation line prevents the fuel tank from being overfilled. Once the nominal filling volume is reached, the roll-over valve closes the refuelling tank ventilation line. Ventilation can only be done via the service tank ventilation line. If refuelling is continued, the throttle will generate excess pressure in the fuel tank. This will make filling significantly harder. The pressure-retaining valve in the left service tank ventilation line limits the excess pressure in the fuel tank.The carbon canister is regenerated by purging with fresh air. The engine control unit opens the tank vent valve. This means there is an intake pipe vacuum at the purge air line. This flushes the carbon canister with fresh air via the tank leakage diagnosis module and the dust filter. The fuel constituents bound by the activated carbon are flushed out by the supplied air and directed via the purge air line to the engine for combustion. This operation is only possible while the engine is running.

Tank safety valve worldwide

See tank safety valve USA with the following exceptions:

  1. The carbon canister has a smaller capacity.
  2. There is no tank leakage diagnosis module (see graphic 3.4, view A)

Leakage diagnosis for the tank ventilation system USA

The tank leak diagnosis module (see drawing 3.4 view A) serves to diagnose leakages for the tank ventilation system within the on-board diagnosis laid down by legislation.

The tank ventilation system is pressurised and the pressure loss is detected in the event of a leak.The tank leak diagnosis module is activated by the engine control unit and detects the pressure loss by way of the power The air required for this purpose is supplied via the dust filter. The pressure test line establishes the connection between fuel tank and fuel filler neck. This enables a leak to be detected in the fuel filler pipe-fuel tank cap area.

Determining fill level in fuel tank:

The fuel tank fluid level is measured with a lever sensor. The lever sensor is fastened to the surge tank.

3.3. Operating data, fuel system

Pressure regulator: 5,0 bar

Operating pressure of the suction jet pump: 1 - 1.3 bar

3.4. Fuel supply system E52

4. Fuel supply system E53

4.1 Part designation

1. Fuel tank (plastic) 15. Expansion tank
2. Fuel pump 16. Anti-flood valve
3. Pressure limit valve 17. Roll-over valve
4. Non-return valve 18. Pressure regulator
5. Fuel filler pipe 19. Fuel filter
6. Fuel tank expansion line 20. Fuel injection pipe
7. Suction jet pump 21. Tank vent valve
8. Run-out protection valve 22. Engine control unit
9. Fuel tank filler cap 23. Intake pipe
10. Fuel delivery line 24. Purge air line
11. Fuel return line 25. Carbon canister
12. Refuelling tank ventilation line 26. Evaporation line
13. Service tank ventilation line 27. Fuel tank leakage diagnosis module
14. Pressure test line (USA only) 28. Dust filter

4.2 Functional description (see also graphic 4.4)

Fuel system

The saddle-shaped fuel tank contains the fuel pump in the smaller, right half. The suction jet pump in the left fuel tank half pumps the fuel through the fuel tank expansion line to the right side of the fuel tank. The suction jet pump is operated via the fuel return line. The pressure limit valve controls the required pressure to operate the suction jet pump. The run-out protection valve secures the fuel return line. If the pressure falls if the fuel return line is damaged or disconnected, the valve closes. This prevents the fuel from running out of the fuel tank in extreme vehicle positions (rollover, on an incline etc.). The non-return valve prevents the fuel from sloshing back into the filler pipe after the fuel pump nozzle is shut.The anti-flood valve on the bottom of the expansion tank protects the system from overfilling when refuelling. The flood valve is closed by rising fuel in the refuelling tank ventilation line and excess pressure is created in the fuel tank preventing further filling.

Fuel supply to the engine

Description see fuel supply system E38/39, 1.2 functional description, engine fuel supply M54/62.

Tank safety valve USA

The fuel tank ventilation during refuelling takes place via the refuelling vent line.Because of its large cross-section, the refuelling ventilation line directs the displaced volume (fuel vapours) at high speed through the expansion tank to the carbon canister. The activated carbon retains the fuel contained in the fuel vapours. The cleaned air is discharged to atmosphere via the evaporation line, the tank leak diagnosis module and the dust filter. Ventilation during vehicle operation is done in the same way via the refuelling tank ventilation line and the service tank ventilation line. The condensed components of the fuel vapour go from the expansion tank via the tank ventilation lines back into the fuel tank. The roll-over valve on the top side of the expansion tank closes if the vehicle rolls over. This prevents fuel from spilling into the carbon canister.The carbon canister is regenerated by purging with fresh air. The engine control unit opens the tank vent valve. This means there is an intake pipe vacuum at the purge air line. This flushes the carbon canister with fresh air via the tank leakage diagnosis module and the dust filter. The fuel constituents bound by the activated carbon are flushed out by the supplied air and directed via the purge air line to the engine for combustion. This operation is only possible while the engine is running.

Tank safety valve worldwide

See tank safety valve USA with the following exceptions:

  1. The carbon canister has a smaller capacity.
  2. There is no tank leakage diagnosis module and dust filter (see graphic 4.4, view A)
  3. There is no pressure test line

Leakage diagnosis for the tank ventilation system USA

Description see fuel supply system E52, 1.2 functional description, leak diagnosis for the tank ventilation system (USA)

Determining fill level in fuel tank:

The fuel level is measured by means of lever sensors on both sides of the fuel tank. The right-hand lever sensor is integrated into the fuel delivery unit. The left-hand lever sensor is located in the left sensor unit. The combination of the determined ohm values from the right and left lever sensor produces the actual fluid level in the fuel tank.

4.3 Operating data, fuel system

Pressure regulator: 3.5 bar

Operating pressure of the suction jet pump: 1 - 1.3 bar

4.4. Fuel supply system E53

5. Fuel supply system E38/39 diesel

5.1 Part designation

1. Fuel tank (E38 steel, E39 plastic) 17.    Dust filter
2. Fuel pump 18.    Fuel return line
3. Surge tank 19.    Fuel delivery line
4. Suction jet pump 20.    H-piece (M47/67)
5. Run-out protection valve 20A 5x distributor (M57)
6. Pressure limit valve 21.    Power distribution box injection pump (M47)
7. Refuelling tank ventilation line 21A High pressure pump (M57/67)
8. Non-return valve 22.    Gear pump (M67)
9. Fuel filler pipe 22A. Inline pump (E38/39 M57)
10. Fuel filler cap 23.    Fuel filter
11. Fuel tank expansion line 24.    Fuel injection pipe (M57/67)
12. Service tank ventilation line 25.    Injector nozzle
13. Service tank ventilation line 26.    Manifold (M67)
14. Auxiliary heater 27.    Bimetal valve 
15. Expansion tank 28.    Fuel cooler
16. Roll-over valve 29.    Pressure limit valve (M57)

5.2 Functional description (see also graphics 5.4/5.5/5.6/5.7)

Fuel system (see graphics 5.4/5.5/5.6/5.7)

Description see fuel supply system E38/39, 1.2 functional description, fuel system.With the following differences:

  1. Both suction jet pumps are operated via the fuel delivery line.
  2. An additional electric auxiliary heater with its own supply line from the fuel tank.
  3. There is no non-return valve in the filler pipe (E38 only)

Fuel supply to the engine

M47 (see graphic 5.4)

The fuel is routed from the electric fuel pump via the fuel delivery line and the fuel filter to the power distribution box injection pump. The distribution box injection pump supplies the respective injector nozzle.The reverse flow from the fuel injector and the power distribution box injection pump goes into the bimetal valve. The bimetal valve divides the amount the fuel return as a function of the fuel temperature.At low fuel temperatures the majority of the fuel goes back into the fuel delivery line before the fuel filter. In this way, the fuel is heated faster at low outdoor temperatures.At high fuel temperatures the majority of the fuel goes via the fuel cooler and the fuel return line back into the fuel tank. Thus, excessive heating of the fuel is avoided at high outside temperatures.Large heated quantities of return fuel may occur in extreme operating conditions such as uphill driving or trailer towing. In this event a small amount of fuel will be sent directly into the fuel delivery line via the throttle in the H-piece. This measure prevents excessive fuel heating in the fuel tank.

M57 (see graphics 5.5/5.6)

The fuel is routed from the electric fuel pump via the fuel delivery line, the inline pump and the fuel filter to the high pressure pump. The high pressure pump supplies the injector nozzles with fuel via the fuel injection pipe.The inline pump generates the required primary fuel pressure for the high pressure pump. This primary pressure is kept constant by the pressure-limiting valve in the engine circuit.The reverse flow from the fuel injector and the high-pressure pump goes into the bimetal valve. The bimetal valve divides the amount the fuel return as a function of the fuel temperature.At low fuel temperatures, the majority of the fuel flows via the 5x distributor back into the fuel delivery line before the inline pump. In this way, the fuel is heated faster at low outdoor temperatures.At high fuel temperatures the majority of the fuel goes via the fuel cooler and the fuel return line back into the fuel tank. Thus, excessive heating of the fuel is avoided at high outside temperatures.Large heated quantities of return fuel may occur in extreme operating conditions such as uphill driving or trailer towing. In this event a small amount of fuel will be sent directly into the fuel delivery line via the throttle in the 5x distributor piece. This measure prevents excessive fuel heating in the fuel tank.

M67 (see graphic 5.7)

The fuel is routed from the electric fuel pump via the fuel delivery line, the fuel filter and the geared pump to the high pressure pump. The high pressure pump supplies the injector nozzles with fuel via the manifold and the fuel delivery lines.The geared pump, which is flanged directly to the high pressure pump, generates the required primary fuel pressure for the high pressure pump. The reverse flow from the fuel injectors and the high pressure pump goes into the bimetal valve (for functional description of the bimetal valve and H-piece see M47). The non-return valve in the H-piece blocks the fuel delivery preventing fuel reverse flow. This prevents pressure drop during times of high fuel requirement.

Tank safety valve

The fuel tank ventilation during refuelling takes place via the refuelling vent line in the fuel filler neck.During operation, the expansion tank and dust filter areas vented from the fuel tank via the service breather lines.The condensed components of the fuel vapour go from the expansion tank via the left service tank ventilation line back into the fuel tank.

Determining fill level in fuel tank:

Description see fuel supply system E38/39, 1.2 functional description, determining fuel tank level.

5.3 Operating data, fuel system

Operating pressure of the fuel pump: 0.4 bar

Operating pressure of the suction jet pumps: 1 - 1.3 bar

5.4. Fuel supply system E39 M47
5.5. Fuel supply system E39 M57
5.6. Fuel supply system E38 M57
5.7 Fuel supply system E38, M67

6. Fuel supply system E46 diesel

6.1 Part designation

1. Fuel tank (E38 steel, E39 plastic) 14.    Service tank ventilation line
2. Fuel pump 15.    Expansion tank
3. Surge tank 16.    Roll-over valve
4. Suction jet pump 17.    Power distribution box injection pump (M47)
5. Fuel tank expansion line          High pressure pump (M57)
6. Run-out protection valve 18.    Inline pump (E38/39 M57)
7. Fuel filler pipe 19.    Fuel filter
8. Fuel filler cap 20.    Fuel injection pipe (M57)
9. Refuelling tank ventilation line 21.    Injector nozzle
10. Fuel return line 22.    Bimetal valve 
11. Fuel delivery line 23.    Fuel cooler
12. H-piece (M47) 24.    Pressure limit valve (M57)
13. Service tank ventilation line  

6.2 Functional description (see also graphics 6.4/6.5)

Fuel system (see graphics 6.4/6.5)

Description see fuel supply system E46, 2.2 functional description, fuel system.With the following differences:

  1. The suction jet pump is operated via the fuel return line.
  2. There is no non-return valve in the filler pipe.
  3. There is no pressure limit valve in the fuel tank

Fuel supply to the engine

M47 (see graphic 6.4)

Description see fuel supply system E38/39 diesel M47, 2.2 functional description, engine fuel supply .

M57 (see graphic 6.5)

Description see fuel supply system E38/39 diesel M57, 2.2 functional description, engine fuel supply.With the following differences:

  1. The H-piece replaces the 5x distributor.
  2. The fuel return line from the bimetal valve is routed directly before the inline pump

Tank safety valve (see graphics 6.4/6.5)

Description see fuel supply system E38/39 diesel M57, 2.2 functional description, engine fuel supply.With the following difference:- The dust filter is omitted.

Determining fill level in fuel tank:

Description see fuel supply system E38/39, 1.2 functional description, determining fuel tank level.

6.3 Operating data, fuel system

Operating pressure of the fuel pump: 0.4 bar

Operating pressure of the suction jet pump: 1 - 1.3 bar

6.4. Fuel supply system E46 M47
6.5. Fuel supply system E46 M57
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